Process of sizing packages of yarn



Patented Apr. 29, 1947 PROCESS OF SIZING PACKAGES F YARN Luther BishopArnold, Jr., Richmond, Va., as-

sig'nor to E. I. du Pont de Nemours & Company, Wilmington, Del, acorporation of Delaware No Drawing.

Application November 6, 1943, Serial No. 509,324

9 Claims- (Cl. 117-101) This invention relates to the sizing ofsynthetic continuous filament yarns in package form. More particularly,it relates to the sizing of spun cakes of water-sensitive cellulosicyarns, such as those of regenerated cellulose. It is especiallyconcerned with the use of aqueous sizing compositions for the sizing ofspun cakes of viscous rayon yarn destined for a-use where high twist isrequired, as in the'knitting of full-fashioned hosiery.

It has been well knownin the art to size continuous filament yarns, suchas viscose rayon yarns, for many uses. Generally, these sizes have beenapplied with the objectives of preserving the yarn against mechanicalinjury during textile operations and/or of lubricating the yarn so thatit will pass through fabrication operations successfully. In addition tothe protective and lubricating properties of the size, a prerequisitehas been water-sensitivity so that the size may be removed from thefabricated structures easily and quickly during the boil-off, whichusually follows.

fabrication. Consequently, these sizes have been formulated to contain aproportion of easily a high degree of twist is required to providesheerness in the knitted structure. Such highly twisted yarns tend tokink, snarl and untwist, properties which may be collectively calledwildness, and the twist must, therefore, be set and held in place atleast partially by the size. Furrayon yarn for fabrication intofull-fashioned hosiery, it has been necessary to wind 9. spun cake to aspool and thence to a skein which may be soaked in a suitable sizecomposition. After the soaked skein has been wrung free 01 excess steamtreatment to set the twist, the size composition helping to hold thetwist after it is set. From this bobbin, the yarn is next transferred toa cone, usually being oiled during the coning operation. The coned yarnis then ready for knitting into full-fashioned hosiery, whereupon theknitted structure may be boiled oil (during which the size is removed),dyed, and finished for consumption.

Yarn has likewise been prepared for use in the knitting offull-fashioned hosiery by winding a previously unsized yarn, which hasbeen highly twisted, onto a spool or other package and iim pregnatingthe wound package of yarn with nonremoved, as by centrifuging, theorganic solvent thermore, a high degree of flexibility must bemaintained in the highly twisted yarn and the customary sizecompositioncapable of setting the twist either makes the yarn too stiff or toosticky to run well in the knitting .machine or deposits such a'brittlesize thatv when the yarn is flexed,

the size flakes ofl, quickly clogging up the very fine openings, as, forexample, in the barbs of the knitting needles, whereupon the yarn breaksand it becomes practically impossible to keep the knitting machine inoperation. I

Knitting sizes have been provided, but they have been applied to theyarn either after the.

twist has been placed in the yarn or, because of their mucilaginouscharacter, they have been applied to the yarn while the latter is inskein form prior to twisting. Thus, in preparing a viscose is removed byevaporation, the binding material serving to maintain the twist in theyarn substantially as it occurred in the yarn prior to the impregnation.

Both of these methods have been fraught with numerous disadvantages.Obviously, the sizing operation which requires passing through theskeining stages exposes the yarn to excess handling and damage besidesbeing expensive and time-consuming. A process which applies a size froman organic solvent solution requires special and expensive apparatus forrecovery of the solvent and the avoidance of fire and health hazards.Furthermore, .the size deposited from the organic solvent is diflicult,if not impossible, to remove from the yarn after the knitting operationhas been completed and, in many instances, requires treating the knittedstructures withorganic solvent to remove the size deposited on the arn.Since this removal is sometimes not thoroughly done, the knittedstructures sufl'er in final operations, such as dyeing, because of thenon-uniform acceptance of the dye caused by traces of the size in, and

the result of the swelling action of the aqueous medium on the celluloseyarn.

It is an object of this invention to provide a process whereby viscose.rayon yarn may be prepared for use especially in the knitting offullfashioned hosiery without undergoing the costly and time-consumingskeining operations. It is also an object of this invention to provide aspun cake of viscose rayon yarn which is sized in cake form and iscapable of conversion to a knitting cone by means of simple twisting,setting and coning operations. It is a further object of this inventionto provide a spun cake of viscose rayon yarn suitable for the knittingof full-fashioned hosiery, wherein the size has been deposited fromaqueous medium. Other objects will be apparent from the followingdescription.

The objects of the invention are attained, in general, by sizing thespun cake of yarn with a non-mucilaginous aqueous sizing compositioncomprising an emulsion of an unctuous, i. e. soapy or waxy, materialhaving a softening point of the order of 30 C. to 70 C. The sizingcomposition is advantageo y applied while it is at a temperature aboutthe same as the softening point of the unctuous material, and the excesscomposition is removed by centrifugal wringing before the sizingcomposition has cooled sufficiently to congeal, and the sized cake isthen submitted to an appropriate drying treatment. The soapy or waxynature of the material insures the maintenance of pliability andflexibility in the yarn during the knitting and similar textileoperations. The low softening point within the specifled range insuresease of application "and sumcient solidity to permit the size to assistin holding the twist and controlling wildness of the yarn while at thesame time binding the numerous filaments of the yarn together duringtextile operations. The non-mucilaginous character of the sizecomposition enables it to be applied to a package, such as a spun cake,to yield a package wherein the individual filaments of each yarn areboundtogether but adjacent yarns, crossing or parallel, in the packageare not stuck together.

In the following examples, which are y ical embodiments of the inventionand intended to illustrate the invention without limiting it to specificdisclosures thereof, the parts are by weight:

Example I A bucket cake of '75-denier 30-filament viscose rayon yarnspun with a left twist of 3 turns, having been washed, desulfured,bleached and dried in the original package form and weighing about 450grams, is wrapped in a protective cheese cloth wrapper to avoid injuryto the yarn on the outside of the cake. I'he wrapped package in umstearate containing about 10% by weight of free stearic acid and 3 gramsof diethylene glycol which had been previously melted together. The bathis maintained at a temperature of C. and the immersion is executedslowly so that no air is trapped within the cake. Thereafter, the cakeis removed from the bath and centrifugally wrung in a perforatedbucket-type extractor having an internal diameter approximating that ofthe external diameter of the dry cake before treatment. The extractionis done immediately after removal of the cake from the bath to avoidundue cooling of the cake and the sizing composition and is conductedfor about 90 seconds at a speed'of about 7,000 B. P. M. in order toreduce the moisture content of the cake to less than 110% of the dryweight of the cake. The extracted cake, still wrapped, is dried for 50hours at about 65 C.

The finished dried cake is found to contain about 9% of sizingcomposition based on the dry weight of the yarn. The individualfilaments of the yarn are held firmly together but the cake structure isfreeand open with substantially no stuck yarns, so that the cake may beback-wound with practically no breaks caused by the sticking together ofadjacent yarns.

Example II Example III A spun cake of yarn istreated in the'mannerdescribed in Example I, using a composition similar to that described inExample II except that the wax mixture thereof'is replaced by a mixtureof 1 part Japan wax and 1 part petrolatum wax (micro-crystallineparafiin wax).

Example IV Example V Y A spun cake of viscose rayon yarn is treated asin Example I, using, however. a bath composed of 90 grams of parafiinwax dispersed by means of collapsed form is subjected to a soakingoperaa wax obtained by esterifying a mixture of approximately 48%stearic, 48% behenic and 4% erucic acids with butyl alcohol, dispersedin, 1800 a colloid mill in 1800 cc. of a 0.5% dispersion of partiallyhydrolyzed polyvinyl acetate.

Example VI A spun cake ofviscose rayon yarn (-denier 30-filament 2.5turns left twist) is immersed in a under the trade-name Lanafin Size 72(sold by Standard Chemical Products (30., of Hoboken, NJ.) for a periodof 1% hours, the bath being cc. of water with a mixture of 10 grams ofsodi- 7 maintained at a temperature of 75 C. In this end of the treatingcycle, the cakes are removed 5.

from the size bath and the excess liquor allowed to drain, whereuponthey are centrifugally wrung as soon as possible to prevent-congealingof the size. The wringing cycle is 90 seconds at about 7,000 R.-P. M.,the wringing bucket having an internal diameter approximating that ofthe external diameter of the dry cake before treatment, in order toreduce the moisture con-. tent of the cake to less than 110% of the dryweight. After wringing. the cakes are dried for '15 48 hours at about 70C. The cakes so treated contain about 8% size based on the dry weight ofthe yarn, and back-winding is excellent.

As has been stated above and as will be readily 6 will depend largely onthe amount of size desired on the finishedv yarn. Emulsions containing.10% to of the sizing composition have given particularly good results.

Thetemperature of the sizing bath is usually selected above thesoftening point of the soapy or waxy material employed; thus,temperatures of 50 C. to 75 C. will be found to be particularly useful.In this way, the emulsion is kept sumciently fluid to insure completeand uniform penetration of the yarn package. In this connection, itshould be observed that after the yarn package has been impregnated withthe emulsion, it should be maintained preferably at about the sametemperature as the sizing bath during the wringing operation in whichthe excess bath is removed in order to prevent congealing of theemulsified sizing composition prior to the removal of the excess.

seen by examination of the above examples, the go While in the examplesthe preferred method of sizing composition of this invention is anaqueous non-mucilaginous emulsion of a soapy or waxy material having asoftening point in the range of 30 C. to 70 C. Among the waxy materialswhich are suitable for use in the practice of this invention may beincluded synthetic (wax) esters of'saturated or partially unsaturatedfatty acids with aliphatic alcohols;- the natural wax-esters, such asjapan wax, carnauba wax and spermaceti; and the crystalline andmicro-crystalline or amorphous paramn waxes. Mixtures of these waxymaterials will frequently be found to be especially useful. Among thesoapy materials which may be included a e the sodium or notassium saltsof partially saponified fats or partially saponified wax-esters in whichthe degree of saponificationand the balance of sodium and/or potassiumsalts has beenadjusted to maintain the soft, wax-like character and tomaintain the softening point of the product withdo in the specifiedrange. It will be apparent, as illustrated by the above examples,.,thatmixtures of these materials may find particular utility. Furthermore,these soapy or waxy materials may be blendedwith small amounts ofmineral oils or vegetable oils to adjust the consistency of the mixturewhich may be found to be dependent-upon the selection of the wax or thetype of yarn undergoing treatment.

When a waxy material of the type described above is selected as theprincipal ingredient of the size, suitable emulsifying materials will beemployed to obtain the dispersion in the aqueous medium. When a soapymaterial, such as a superfatted soap, is selected as the principalingredient, in many instances the soap will constitute its ownemulsifying agent or it may serve as the emulsifying agent for-a waxymaterial.

Suitable emulsifiers include the sodium and Do- 00 tassium salts offatty acids; sulfated vegetable oils; mineral oil sulfonates; andsynthetic emulsifiers, such as metallic and amine salts of sulfatedfatty alcohols, the sodium salt of taurine oleamide, the half fatty acidester of ethylene glycol 65 and the partial fatty acid esters ofsorbitol or its dehydration products. In using sodium or potassiumsaltsof-fatty acids, it is frequently desirable to include ahomogenizer, such as diethylene glycol, the monobutyl ether of ethylenegly- 7o col, or the lower aliphatic alcohols, such as isopropyl or butylalcohol.

The sizing composition. may be dispersed in the aqueous medium so thatit constitutes from immersion treatment is set forth, it is to beunderstood, of course, that the yarn package may sion through thepackage structure under pressure, as, for example, from the interior ofthe package to the exterior.

While it is preferred in the practice of this invention to apply thesizing composition to a dried spun cake which is free from otherfinishing compositions, the nature of the sizing composition and theprocess permit wide latitude of action. Thus, the sizing compositionmaybe applied to yarn already containing a finish. This is ofoutstanding utility in a viscose rayon manufacturing plant producingyarn, a minor portion of which is destined for full-fashioned knittingoperations, the remainder being destined for other uses. In such a case,the entire production may be given the conventional finishing treatmentprior to ini- Because of the teachings of the-prior art, it

was indeed surprising that a spun cake of viscose. rayon yarn could beimpregnated with the sizing composition applied through the medium of anaqueous emulsion. The success of the treatment may be attributed .to thewaxy or soapy character of the essential sizing material. It was,indeed, still further surprising that emulsions of such highconcentration could be used with the resultant deposition of relativelylarge amounts of size on the yarn, which size would bind the filamentsof individual yarns firmly together without at the same time causingadjacent yarns to stick together.

. The practice of this invention affords numerous advantages over theprior art. Since the size composition is applied from an aqueous medium,the process is economical and .numerous health and fire hazards areavoided. Contrary to expectations, the size is uniformly distributedthroughout "the package; even the innermost yams of. the spun cakes arethoroughly impregnated. I

.These sized packages of yarn do not suffer from the phenomenon known as'wicking, a term 5% to 25% of theemulslon. The'concentraticn which 'isused to describe the migration of the 7 size to the outer portions or apackage, as,;for example, at the shoulders of a spun cake of rayon yarn.The resulting increased concentration of the size on the externalconvolutions of'the package cause sticking, snarling, discoloration andnumerous other undesirable characteristics, particularly when attemptsare made to back-wind the yarn from the spun cake.

Spun cakes of viscose rayon sized according to the present inventionexhibit a remarkable freeness of structure so that as many as 100 driedsized cakes may be back-wound to spools with only one or two breaks inthe yarn caused by the sticking together of adjacent yarns in the spuncake. As a matter of fact, the yarn may be backwound directly in athrowing operation, thus avoiding any preliminary spooling. In this way,the yarn is thrown directly to the bobbin customarily used for settingthe twist and, after steaming the yarn on that bobbin, the yarn may betransferred to a cone destined for use on the knitting machine. Therunning properties of the yarns sized according to this invention areexcellent, particularly in knitting machines which yield fiat-knitfabrics, as in the manufacture of full-fashioned hosiery. The size doesnot flake of! on the knitting needles and sinker bars. It does not stickto the guide or snappers during a temporary shut-down of the knittingmachine, which sticking would result in what is known in the art as apressoil when the machine is again started. The size softenssufficiently to enable the formation of regular stitches of uniform sizeand to cement the loops together when the fabric dries. It affordssufficient lubrication so that the yarn passes through the machinearound the needles and sinker bars without cutting or snagging. The yarnis rendered flexible and capable of meeting the exacting requirements ofthe full-fashioned hosiery knitting process. The size assists in thesettingof the twist in the yarn so that wildness is controlled.

The sizing composition is easily removed in later processing because ofits dispersibility in aqueous mediaand, because it is so easily scouredfrom the yarn, it does not interfere with the uniformity of dyeing ofthe finished materials.

As a matter of fact, in those embodiments of.

the invention which utilize soapy materials, the uniformity of thedyeing is improved since many dyes soaps; thus, the uniformity in depthof dyeing is advantageously affected.

Many knitters prefer to operate. their knitting machines using yarnswhich have been wetted with water in the so-called dip-trough of theknitting machine. Utilizing yarns of the present invention, thedip-trough may be eliminated or, if it is used, the size composition isamenable to dampening with water, a characteristic which distinguishesit from yarn which has been sized by deposition of organicsolvent-soluble material inthe absence of proper emulsifying andhomogenizing material.

Since it is obvious that many changes and modifications can be made inthe above-described details without departing from the nature and spiritof the invention, it is to be understood that the invention is not to belimited theretoexcept as set forth in the appended claims. I claim:

1. A process for sizing a dried spun cake of rayon which comprisesimpregnating said cake withan aqueous emulsion of a non-mucilaginousunctuous material having a softening point of are applied to fabrics inthe presence of the order of 30 C, to 70 (Land selected from the classwhich consists of soapy and waxy materials, said emulsion being at atemperature at least equal to the softening point of saidnonmucilaginous unctuous material, and removing the excess emulsionbefore the emulsion has congealed, the impregnated cake being maintainedduring the removal of the excess emulsion at a temperature substantiallythe same as that of the emulsion during the impregnation step.

2. A process for sizing a dried spun cake of rayon which comprisesimpregnating said cake with an aqueous emulsion of a non-mucilaginousunctuous material having a softening point of the order of 30 C. to 70C. and selected from the class which consists of soapy and waxymaterials, 'said emulsion being at a temperature at least equal to thesoftening point of said nonmucilaginous unctuous material, andcentrifugally wringing the impregnated cake to remove the excessemulsion, the impregnated cake being maintained during the removal ofthe excess emulsion at a temperature substantially the same as that ofthe emulsion during the impregnation step. i

3. A process for sizinga dried spun cake of rayon which comprisesimpregnating said cake with an aqueous emulsion of a non-mucilaginousunctuous material having a softening point of the order of 30 C. to 70,C. and selected from the class which consists of soapy and waxymaterials, said emulsion being at a temperature at least equal-to thesoftening point of said nonmucilaginous unctuous material, centrifugallywringing the cake to remove excess emulsion and reduce the moisturecontent thereof to less than 110% of the dry weight of the cake, theimpregnated cake being maintained during the removal of the excessemulsion at a temperature substantially the same as that of the emulsionduring the impregnation step, and drying the cake.

4. A process for sizing a dried spun cake of rayon which comprisesimpregnating said cake with an aqueous emulsionof a non-mucilaginousunctuous material having a softening point of the order of 30 C. to 70C. and selected from the class which consists of soapy and waxymaterials, said emulsion 'being at a temperature at least equal to thesoftening point of said nonmucilaginous unctuous material, centrifugallywringing the cake before the size has congealed to remove excessemulsion and reduce the mois- ,ture content thereof to less than 110% ofthe dry weight of the cake, the impregnated cake being maintained duringthe removal of the excess emulsion at a temperature substantially thesameas that of the emulsion during the impregnation step, and drying thecake.

5. A process for sizing a dried spun cake of rayon which comprisesimpregnating said cake with an aqueous emulsion of a non-mucilaginousunctuous material having a softening point of the order of 30 C. to C.and selected from the class which consists of soapy and waxy materials,said emulsion being at a temperature at least equal to the softeningpoint of said non-mucilaginous unctuous material, centrifugally wringingthe cake at about the same temperature as the temperature of theemulsion to remove excess emulsion and reduce the moisture contentthereof to less than of the dry weight of the cake, and drying the cake.

6. A process for sizing a dried spun cake of viscose rayon whichcomprises impregnating said cake with an aqueous emulsion of a waxymaterial having a softening point of the order of 30 C. to 70 0., saidemulsion being at a temperature at least equal to the softening point ofsaid waxy material, and removing the excess emulsion before it hascongealed, the impregnated cake bein maintained during the removal ofthe excess emulsion at atemperature substantially the same as that ofthe emulsion during the impregnation step.

7. A process for sizinga dried spun cake of viscose rayon whichcomprisesimpregnating said cake with an aqueous emulsion of a waxy materialhaving a softening point of the order of 30 C. to 70 0., said emulsionbeing at a temperature at least equal to the softening point of saidwaxy material, and centrifugally wringing the cake to remove the excessemulsion before it has congealed, the impregnated cake being maintainedduring the removal of the excess emulsion at a temperature substantiallythe same as that of the emulsion during the impregnation step.

8.4 process for sizing a dried spun cake of viscose rayon whichcomprises immersing said cake in a bath comprising an aqueous emulsionof a waxy material having a softening point of the order of 30.C. to. 700., said bath being maintained at a temperature at least equal to thesoftening point of said waxy material, the immersion being executedslowly to inhibit trapping of air in said cake, removing the cake from10 the bath, centrifugally wringing the impregnated cake before the sizehas congealed until the moisture content thereof is less than 110% ofthe dry weight of the cake, and subjecting the cake to a'drying'treatment.

9. A process as set forth in claim 8 wherein the bath is maintained at50 C. and comprises 120 parts of a wax, obtained by esterlfying amixture of approximately 48% stearlc, 48% behenic and 4% erucic acidswith butyl alcohol,

dispersed in 1800 parts of water.

LUTHER BISHOP ARNOLD, JR.

REFERENCES CITED The followingreferences are of record in the file ofthis patent:

UNITED STATES PATENTS

